1. Field of the Invention
The present invention relates to novel oil extended polystyrene compositions. More particularly, it pertains to a polymer gel blend of syndiotactic polystyrene, a rubbery elastomer and an extender oil.
2. Description of Prior Art
A styrenic polymer having syndiotactic configuration (sPS) is excellent in heat resistance and chemical resistance but displays a high Shore A hardness and is poor in impact resistance, flexibility and elasticity and therefore, the potential usage of this polymer has certain limitations. In order to solve the above-mentioned problem, attempts have been made to improve the impact resistance of sPS, for example, by blending a rubbery elastomer and/or other thermoplastic resin with sPS as displayed in U.S. Pat. Nos. 5,391,611; 5,395,890; and 5,247,020. However none of these patents disclose improvements in the blends resulting in softness, flexibility, elasticity and/or damping characteristics or the inclusion of oil or other extenders to achieve these properties.
It has been known in the past to extend thermoplastic elastomers with petroleum base oils such as naphthenic, aromatic and paraffinic oils and other low weight molecular organic materials in order to reduce costs and to improve the elastomeric properties of certain of the thermoplastic elastomers. In U.S. Pat. No. 5,451,454, owned by the current assignee, a blend of a high-molecular weight block copolymer having a hard block and a soft block and a large volume of oily or low molecular weight material provides a composition having unique softness, adequate mechanical strength and damping properties useful in many industrial applications. The heat resistance of this composition was not adequate for higher temperature applications including many uses in automobiles and electrical appliances.
It is extremely desirable to prepare a polymer composition having elastomeric characteristics, good mechanical strength, unique softness and various utilities in high temperature applications.